I understand where AZ is coming from. I'm a white male gun owner who lives in one of the states with a reputation as a stronghold for "Aryan militias". They already try to tie groups like the Three Percenters, and heck, even the Idaho Freedom Foundation, into "white power militias". All it takes is an Elizabeth Warren presidency to suddenly make me a domestic terrorist because white, man, gun owner in Idaho, who wears Gadsden t-shirts.
On the other hand, I despise what antifa represents and what they do. Their violence is out of hand and to this point, goes largely unpunished, for example, in places like Portland where the local government practically protects them.
In BenWorld, rather than make them (or anyone) a terrorist organization, my solution would be that when some black clad jackass tries to bash my head in with a bike lock, I put 2-3 rounds in him, and when the cops show up they say, "nice grouping". In this world, I'm just as likely to be sent to the pokey for that, which allows their jackassery to thrive.